Seal plates for chemical vapor infiltration &amp; deposition chambers

ABSTRACT

A seal plate disposable between a pair of preforms for chemical vapor infiltration is disclosed. The seal plate may include a plurality of first channels that extend completely through the seal plate and that are located between an inner annulus and outer annulus of the seal plate. The seal plate may further include a plurality of second channels that also extend completely through the seal plate and that are located also between an inner annulus and outer annulus. The first channels may differ from the second channels in at least one respect (e.g., the first channels may be of a different width than the second channels). The first channels may provide an inlet for the chemical vapor infiltration of the preform, while the second channels may provide an outlet for the chemical vapor infiltration of the preform.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/819,545, filed Mar. 16, 2020, entitled “SEAL PLATES FOR CHEMICALVAPOR INFILTRATION & DEPOSITION CHAMBERS” which is incorporated byreference herein in its entirety for all purposes.

FIELD

The present disclosure generally relates to the field of chemical vaporinfiltration and deposition chambers and, more particularly, to spacersdisposed between adjacent pairs of preforms in such chambers.

BACKGROUND

Chemical vapor infiltration and deposition (CVI/CVD) is a known processfor making composite structures such as carbon/carbon brake disks. TheCVI/CVD process typically used for making carbon/carbon brake disks mayinvolve passing a reactant gas or gas mixture (e.g., methane, propane,etc.) around heated porous structures (e.g., carbonized preforms) with apressure differential driving the gas mixture into the porousstructures. The gas enters into the porous structures, driven bypressure gradients, and undergoes a reaction such as thermaldecomposition, hydrogen reduction, co-reduction, oxidation,carbonization, or nitridation to deposit a binding matrix.

Depending on CVI/CVD methodology and conditions, the porous structuremay not densify at a uniform rate across the thickness of a porousstructure, may not form a desired microstructure, and may be associatedwith long processing times. Thus, creation of uniformly densified porousstructures may be impaired using conventional systems and methods.

SUMMARY

The present disclosure encompasses and/or embodies a seal plate fordisposition in a chemical vapor infiltration and deposition chamber. Theseal plate may include a plurality of channels that extend completelythrough the seal plate. Such a plurality of channels may include aplurality of first channels, along with a plurality of second channels.

The seal plate may be in the form of a thin structure, with a maximumthickness being about 0.5″ (12.7 mm) in various embodiments and about0.15″ (3.81 mm) in various embodiments. Any appropriate material orcombination of materials may be utilized for the seal plate, includingwithout limitation Carbon/Carbon (C/C), Silicon Carbide (SiC) or otherrefractory type materials that can withstand CVD temperatures. A body ofthe seal plate may include a plurality of fibers, such as carbon fibers,fiber-reinforced silicon carbide (SiC), Grafoil® (UCAR graphite basedmaterial), or any combination thereof. The seal plate may be densifiedby CVI/CVD.

The seal plate may have an opening (e.g., centrally disposed). An innerperimeter of the seal plate may define a boundary of this opening, andan outer perimeter may be spaced (e.g., outwardly) from this innerperimeter. Such an inner perimeter and outer perimeter for the sealplate may be concentrically disposed, such that the outer perimeter maybe characterized as being disposed radially outwardly from the innerperimeter.

A plurality of first channels may extend through the seal plate. Whatmay be characterized as a first end of these first channels may bespaced outwardly from the above-noted inner perimeter of the seal plate,while what may be characterized as a second end of these first channelsmay be spaced inwardly from the above-noted outer perimeter of the sealplate, with the first end of each of the first channels being positionedcloser to the inner perimeter than their corresponding second end. Thefirst end of each of the first channels may be disposed a commondistance from the inner perimeter, the second end of each of the firstchannels may be disposed a common distance from the outer perimeter, orboth. Various embodiments has/have the width of each first channelprogressively increasing proceeding from its corresponding first end toits corresponding second end (e.g., increasing at a constant rate). Eachfirst channel may have a minimum width, proceeding along itscorresponding length dimension, of about 0.25″ (6.35 mm) in variousembodiments. A centerline of each of the plurality of first channels(e.g., that extends from a first end to a corresponding second end of agiven first channel) may be disposed along a radius extending from acenter of the seal plate.

A plurality of second channels may extend through the seal plate. Whatmay be characterized as a first end of these second channels may bespaced outwardly from the above-noted inner perimeter of the seal plate,while what may be characterized as a second end of these second channelsmay be spaced inwardly from the above-noted outer perimeter of the sealplate, with the first end of each of the second channels beingpositioned closer to the inner perimeter than their corresponding secondend. The first end of each of the second channels may be disposed acommon distance from the inner perimeter, the second end of each of thesecond channels may be disposed a common distance from the outerperimeter, or both. Various embodiments has/have the width of eachsecond channel progressively increasing proceeding from itscorresponding first end to its corresponding second end (e.g.,increasing at a constant rate). Each second channel may have a minimumwidth, proceeding along its corresponding length dimension, of about0.25″ (6.35 mm) in various embodiments. A centerline of each of theplurality of second channels (e.g., that extends from a first end to acorresponding second end of a given second channel) may be disposedalong a radius extending from a center of the seal plate.

At least one second channel may be disposed between each adjacent pairof first channels. Various embodiments has/have a single second channelbeing disposed between each adjacent pair of first channels. Theplurality of first channels may be characterized as being offset in aradial dimension relative to each of the plurality of second channels.

The first end of each first channel may be disposed closer to the innerperimeter of the seal plate than the first end of each second channel.The second end of each second channel may be disposed closer to theouter perimeter of the seal plate than the second end of each firstchannel. The width of the first end of each first channel may be greaterthan the width of the first end of each second channel. The width of thesecond end of each first channel may be greater than the width of thesecond end of each second channel.

The seal plate may include both an inner annulus and an outer annulus.Each channel that extends through the seal plate may extend from theinner annulus to the outer annulus. None of the channels used by theseal plate extend into the inner annulus or the outer annulus in variousembodiments (e.g., the inner annulus, the outer annulus, or both may befree of one or more openings, one or more slots that extend partiallythrough the seal plate, and/or may be free of one or more channels orother apertures that extend completely through the seal plate). Aminimum width of the inner annulus is about 0.25″ (6.35 mm) in variousembodiments. A minimum width of the outer annulus is about 0.25″ (6.35mm) in various embodiments.

The seal plate may be characterized as including an upper surface and anoppositely disposed lower surface, the distance between which may becharacterized as defining a thickness of the seal plate. One oralignment features may be included on at least one of the upper andlower surfaces of the seal plate, for instance to facilitate positioninga preform thereon. An inner alignment feature may be included on atleast one of the upper and lower surfaces of the seal plate (e.g., suchthat a preform positioned on the seal plate is not disposed inwardly ofsuch an alignment feature). An outer alignment feature may be includedon at least one of the upper and lower surfaces of the seal plate (e.g.,such that a preform positioned on the seal plate is not disposedoutwardly of such an alignment feature). Any such inner alignmentfeature, any such outer alignment feature, or both may be in the form ofa mark, groove, or the like. When both an inner alignment feature and anouter alignment feature are utilized, these alignment features may beconcentrically disposed relative to one another, including in relationto an inner perimeter and/or an outer perimeter of the seal plate.

A preform stack for disposition in a chemical vapor infiltration anddeposition chamber may include a pair of the above-noted seal plates,with a preform being disposed between and engaged by these seal plates.At least part of each first channel used by these seal plates may extendinwardly beyond an inner perimeter of the preform, and may define aninlet for introducing a gaseous medium into the corresponding firstchannel. One or more inner alignment features may be utilized to realizesuch a positioning. At least part of each second channel used by theseal plates may extend outwardly beyond an outer perimeter of thepreform, and may define an outlet for allowing a gaseous medium to exitthe corresponding second channel. One or more inner alignment featuresmay be utilized to realize such a positioning. A chemical vaporinfiltration and deposition chamber may be pressurized such that agaseous medium enters each first channel through a corresponding andabove-described inlet, and such that a gaseous medium exits each secondchannel through a corresponding and above-described outlet (e.g., a highpressure region in the chemical vapor infiltration and depositionchamber may be disposed radially inward of a low pressure region in thechemical vapor infiltration and deposition chamber, including where sucha low pressure region corresponds with/includes the above-describedopening in each seal plate within the preform stack).

Various aspects are also addressed by the following paragraphs and inthe noted combinations:

1. A seal plate disposable between a pair of preforms in a chemicalvapor infiltration and deposition chamber, comprising:

-   -   a body comprising an opening, an inner perimeter that defines a        boundary of said opening, an outer perimeter spaced from said        inner perimeter, an upper surface, and a lower surface that is        spaced from said upper surface to define a thickness of said        body;    -   a plurality of first channels that extend completely through        said thickness of said body, wherein a first end of each first        channel of said plurality of first channels is spaced outwardly        from said inner perimeter, wherein a second end of each said        first channel is spaced inwardly from said outer perimeter, and        wherein said first end of each said first channel is positioned        closer to said inner perimeter than its corresponding said        second end;    -   a plurality of second channels that extend completely through        said thickness of said body proceeding from said upper surface        to said lower surface, wherein a first end of each second        channel of said plurality of second channels is spaced outwardly        from said inner perimeter, wherein a second end of each said        second channel is spaced inwardly from said outer perimeter, and        wherein said first end of each said second channel is positioned        closer to said inner perimeter than its corresponding said        second end;    -   wherein each of said plurality of first channels is different        from each of said plurality of second channels.

2. The seal plate of paragraph 1, wherein said body comprises aplurality of fibers selected from the group consisting of carbon,silicon carbide, or any combination thereof.

3. The seal plate of any of paragraphs 1-2, wherein said inner perimeterand said outer perimeter are each circular and concentrically disposed.

4. The seal plate of any of paragraphs 1-3, wherein said first end ofeach said first channel is disposed a common distance from said innerperimeter.

5. The seal plate of any of paragraphs 1-4, wherein said second end ofeach said first channel is disposed a common distance from said outerperimeter.

6. The seal plate of any of paragraphs 1-5, wherein said first end ofeach said second channel is disposed a common distance from said innerperimeter.

7. The seal plate of any of paragraphs 1-6, wherein said second end ofeach said second channel is disposed a common distance from said outerperimeter.

8. The seal plate of any of paragraphs 1-7, wherein a width of each saidfirst channel progressively increases proceeding from its correspondingsaid first end to its corresponding said second end.

9. The seal plate of any of paragraphs 1-7, wherein said width of eachsaid first channel increases at a constant rate proceeding from itscorresponding said first end to its corresponding said second end.

10. The seal plate of any of paragraphs 1-9, wherein a width of eachsaid second channel progressively increases proceeding from itscorresponding said first end to its corresponding said second end.

11. The seal plate of any of paragraphs 1-9, said width of each saidsecond channel increases at a constant rate proceeding from itscorresponding said first end to its corresponding said second end.

12. The seal plate of any of paragraphs 1-11, wherein said first end ofeach said first channel is closer to said inner perimeter than saidfirst end of each said second channel.

13. The seal plate of any of paragraphs 1-12, wherein said second end ofeach said second channel is closer to said outer perimeter than saidsecond end of each said first channel.

14. The seal plate of any of paragraphs 1-13, wherein a width of saidfirst end of each said first channel is greater than a width of saidfirst end of each said second channel.

15. The seal plate of any of paragraphs 1-14, wherein a width of saidsecond end of each said first channel is greater than a width of saidsecond end of each said second channel.

16. The seal plate of any of paragraphs 1-15, wherein said thickness ofsaid body is no more than about 0.5″ (12.7 mm).

17. The seal plate of any of paragraphs 1-16, wherein a centerline ofeach of said plurality of first channels and each of said plurality ofsecond channels are disposed along a separate radius.

18. The seal plate of any of paragraphs 1-17, wherein at least one saidsecond channel is disposed between each adjacent pair of said firstchannels.

19. The seal plate of any of paragraphs 1-17, wherein one said secondchannel is disposed between each adjacent pair of said first channels.

20. The seal plate of any of paragraphs 1-19, wherein said body furthercomprises an inner annulus and an outer annulus, wherein each of saidplurality of first channels and each of said plurality of secondchannels are located entirely between said inner annulus and said outerannulus.

21. The seal plate of paragraph 20, wherein a minimum width of saidinner annulus is about 0.25″ (6.35 mm).

22. The seal plate of any of paragraphs 20-21, wherein a minimum widthof said outer annulus is about 0.25″ (6.35 mm).

23. The seal plate of any of paragraphs 1-22, wherein a minimum width ofsaid first end of each said first channel is about 0.25″ (6.35 mm).

24. The seal plate of any of paragraphs 1-22, wherein a width of saidfirst end of each said first channel is within a range of about 0.5″(12.7 mm) to about 2″ (50.8 mm).

25. The seal plate of any of paragraphs 1-24, further comprising aninner alignment feature on said upper surface and an outer alignmentfeature on said upper surface.

26. The seal plate of paragraph 25, wherein said inner alignment featurecomprises at least one first alignment groove and wherein said outeralignment feature comprises at least one second alignment groove.

27. The seal plate of paragraph 26, wherein each said first alignmentgroove is disposed outwardly of said first end of each said firstchannel and intersects a corresponding adjacent pair of said firstchannels.

28. The seal plate of any of paragraphs 26-27, wherein each said secondalignment groove is disposed inwardly of said second end of each saidsecond channel and intersects a corresponding adjacent pair of saidsecond channels.

29. A preform assembly comprising a preform, a first said seal plate ofany of paragraphs 25-28, and a second said seal plate of any ofparagraphs 25-28, wherein said preform is disposed between and contactseach of said first said seal plate and said second said seal plate,wherein an inner perimeter of said preform is aligned with said inneralignment feature, and wherein an outer perimeter of said preform isaligned with said outer alignment feature.

30. A chemical vapor infiltration and deposition chamber comprising afirst said seal plate of any of paragraphs 1-28, a second said sealplate of any of paragraphs 1-28, and a preform disposed between andcontacting each of wherein said first said seal plate and said secondsaid seal plate.

31. The chemical vapor infiltration and deposition chamber of paragraph30, wherein a high pressure side of said chemical vapor infiltration anddeposition chamber is associated with said inner perimeter of each ofsaid first said seal plate and said second said seal plate, and whereina low pressure side of said chemical vapor infiltration and depositionchamber is associated with said outer perimeter of each of said firstsaid seal plate and said second said seal plate.

32. The chemical vapor infiltration and deposition chamber of paragraph31, wherein said first channels comprise inlets channels and said secondchannels comprise outlet channels.

33. A preform stack for disposition in a chemical vapor infiltration anddeposition chamber, comprising:

-   -   a preform comprising an upper preform surface and a lower        preform surface;    -   a first seal plate disposed on and contacting said upper preform        surface; and a second seal plate disposed on and contacting said        lower preform surface, wherein each of said first seal plate and        said second seal plate comprises:        -   a body comprising an opening, an inner perimeter that            defines a boundary of said opening, an outer perimeter            spaced from said inner perimeter, an upper surface, and a            lower surface that is spaced from said upper surface;        -   a plurality of first channels that extend completely through            said body from said upper surface to said lower surface,            wherein a first end of each first channel of said plurality            of first channels is spaced outwardly from said inner            perimeter, wherein a second end of each said first channel            is spaced inwardly from said outer perimeter, and wherein            said first end of each said first channel is positioned            closer to said inner perimeter than its corresponding said            second end.

34. The preform stack of paragraph 33, wherein said preform comprises aplurality of first fibers.

35. The preform stack of any of paragraphs 33-34, wherein said bodycomprises a plurality of second fibers.

36. The preform stack of any of paragraphs 33-35, wherein said innerperimeter and said outer perimeter are each circular and concentricallydisposed.

37. The preform stack of any of paragraphs 33-36, wherein said first endof each said first channel is disposed a common distance from said innerperimeter.

38. The preform stack of any of paragraphs 33-37, wherein said secondend of each said first channel is disposed a common distance from saidouter perimeter.

39. The preform stack of any of paragraphs 33-38, wherein a width ofeach said first channel progressively increases proceeding from itscorresponding said first end to its corresponding said second end.

40. The preform stack of any of paragraphs 33-38, a width of each saidfirst channel increases at a constant rate proceeding from itscorresponding said first end to its corresponding said second end.

41. The preform stack of any of paragraphs 33-40, wherein a minimumwidth of said first end of each said first channel is about 0.25″ (6.35mm).

42. The preform stack of any of paragraphs 33-40, wherein a width ofsaid first end of each said first channel is within a range of about0.5″ (12.7 mm) to about 2″ (50.8 mm).

43. The preform stack of any of paragraphs 33-42, further comprising analignment feature on said upper surface.

44. The preform stack of any of paragraphs 33-42, wherein said bodyfurther comprises a plurality of second channels that extend completelythrough said thickness of said body proceeding from said upper surfaceto said lower surface, wherein a first end of each second channel ofsaid plurality of second channels is spaced outwardly from said innerperimeter, wherein a second end of each said second channel is spacedinwardly from said outer perimeter, and wherein said first end of eachsaid second channel is positioned closer to said inner perimeter thanits corresponding said second end.

45. The preform stack of paragraph 44, wherein each of said plurality offirst channels is different from each of said plurality of secondchannels.

46. The preform stack of any of paragraphs 44-45, wherein said first endof each said second channel is disposed a common distance from saidinner perimeter.

47. The preform stack of any of paragraphs 44-46, wherein said secondend of each said second channel is disposed a common distance from saidouter perimeter.

48. The preform stack of any of paragraphs 44-47, wherein a width ofeach said second channel progressively increases proceeding from itscorresponding said first end to its corresponding said second end.

49. The preform stack of any of paragraphs 44-47, wherein said width ofeach said second channel increases at a constant rate proceeding fromits corresponding said first end to its corresponding said second end.

50. The preform stack of any of paragraphs 44-49, wherein said first endof each said first channel is closer to said inner perimeter than saidfirst end of each said second channel.

51. The preform stack of any of paragraphs 44-50, wherein said secondend of each said second channel is closer to said outer perimeter thansaid second end of each said first channel.

52. The preform stack of any of paragraphs 44-51, wherein a width ofsaid first end of each said first channel is greater than a width ofsaid first end of each said second channel.

53. The preform stack of any of paragraphs 44-52, wherein a width ofsaid second end of each said first channel is greater than a width ofsaid second end of each said second channel.

54. The preform stack of any of paragraphs 44-53, wherein a centerlineof each of said plurality of first channels and each of said pluralityof second channels are disposed along a separate radius.

55. The preform stack of any of paragraphs 44-54, wherein at least onesaid second channel is disposed between each adjacent pair of said firstchannels.

56. The preform stack of any of paragraphs 44-55, wherein one saidsecond channel is disposed between each adjacent pair of said firstchannels.

57. The preform stack of any of paragraphs 44-56, wherein said firstchannels extend beyond an inner perimeter of said preform and saidsecond channels extend beyond an outer perimeter of said preform.

58. The preform stack of any of paragraphs 44-56, wherein said first endof each said first channel is disposed inwardly of an inner perimeter ofsaid preform and a remainder of each said first channel accesses one ofsaid upper preform surface and said lower preform surface, wherein saidsecond end of each said second channel is disposed outwardly of an outerperimeter of said preform and a remainder of each said second channelaccesses one of said upper preform surface and said lower preformsurface.

59. The preform stack of any of paragraphs 44-58, wherein said bodyfurther comprises an inner annulus and an outer annulus, wherein each ofsaid plurality of first channels and each of said plurality of secondchannels are located entirely between said inner annulus and said outerannulus.

60. The preform stack of paragraph 59, wherein a minimum width of saidinner annulus is about 0.25″ (6.35 mm).

61. The preform stack of any of paragraphs 59-60, wherein a minimumwidth of said outer annulus is about 0.25″ (6.35 mm).

62. The preform stack of any of paragraphs 44-61, further comprising aninner alignment feature on said upper surface and an outer alignmentfeature on said upper surface.

63. The preform stack of paragraph 62, wherein said inner alignmentfeature comprises at least one first alignment groove and wherein saidouter alignment feature comprises at least one second alignment groove.

64. The preform stack of paragraph 63, wherein each said first alignmentgroove is disposed outwardly of said first end of each said firstchannel and intersects a corresponding adjacent pair of said firstchannels.

65. The preform stack of any of paragraphs 63-64, wherein each saidsecond alignment groove is disposed inwardly of said second end of eachsaid second channel and intersects a corresponding adjacent pair of saidsecond channels.

66. The preform stack of any of paragraphs 62-65, wherein an innerperimeter of said preform is aligned with said inner alignment featureand an outer perimeter of said preform is aligned with said outeralignment feature.

67. The preform stack of any of paragraphs 33-66, further comprising:

-   -   a second said preform, wherein said first seal plate is disposed        between and engages each of said preform and said second said        preform, where said preform closes one side of a first length        portion of each of said plurality of first channels and said        second said preform closes an opposite side of said first length        portion of each of said plurality of first channels.

68. The preform stack of any of paragraphs 33-67, wherein said thicknessof said body is no more than about 0.5″ (12.7 mm).

69. A method of processing a preform, comprising the steps of:

-   -   disposing a preform in a chamber between first and second seal        plates that engage opposing surfaces of said preform, wherein        each of said first and second seal plates comprises a plurality        of first channels that each provide an open space that directly        interfaces with one of said opposing surfaces of said preform;    -   directing a gaseous medium into said chamber;    -   introducing said gaseous medium into each of said plurality of        first channels;    -   increasing a surface area of said preform that is exposed to        said gaseous medium within each of said plurality of first        channels when proceeding in a first direction along each of said        plurality of first channels; and depositing a material within an        interior of said preform using said gaseous medium.

70. The method of paragraph 69, wherein said preform comprises an innerperimeter and an outer perimeter, and wherein said first direction istoward said outer perimeter of said preform.

71. The method of paragraph 70, further comprising:

-   -   introducing said gaseous medium into an inlet zone of said        chamber that is located inwardly of said inner perimeter of said        preform.

72. The method of paragraph 71, wherein said first direction is towardan exit zone that is at a lower pressure than said inlet zone and thatis located outwardly of said inlet zone.

73. The method of paragraph 72, wherein each of said first and secondseal plates comprise an interior opening, an outer perimeter, and aninner perimeter that defines a boundary of said interior opening,wherein said inlet zone comprises said interior opening of each of saidfirst and second seal plates.

74. The method of any of paragraphs 69-73, further comprising:

-   -   disposing a second said preform in said chamber, wherein said        first seal plate is disposed between and engages each of said        preform and said second said preform.

75. The method of paragraph 74, further comprising:

-   -   simultaneously exposing a portion of each of said preform and        said second said preform to said gaseous medium within each of        said plurality of first channels of said first seal plate.

76. The method of any of paragraphs 69-75, further comprising:

-   -   introducing said gaseous medium into said plurality of first        channels of each of said first and second seal plates through a        first end portion of each of said plurality of first channels        that extends inwardly beyond said preform.

77. The method of any of paragraphs 69-76, further comprising:

-   -   providing an outlet for said gaseous medium between each        adjacent pair of said plurality of channels of said first and        second seal plates.

78. The method of paragraph 77, wherein said outlet comprises aplurality of second channels that are spaced relative to each of saidplurality of first channels.

79. The method of paragraph 78, further comprising:

-   -   exiting said gaseous medium from said preform through a second        end portion of each of said plurality of second channels that        extends outwardly beyond said preform.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a chemical vapor infiltration and deposition vesselfor densifying a stack of porous preforms, and that utilizes inner andouter seal plates;

FIG. 2 is a perspective view of a seal plate that may disposed betweeneach adjacent pair of preforms in the chemical vapor and depositioninfiltration vessel of FIG. 1 ;

FIG. 3 is a perspective view of a seal plate that may disposed betweeneach adjacent pair of preforms in the chemical vapor and depositioninfiltration vessel of FIG. 1 , and that incorporates preform alignmentfeatures;

FIG. 4 is a perspective view of the seal plate of FIG. 3 , with apreform positioned thereon;

FIG. 5 is a view of a portion of a lower surface of the seal plate ofFIG. 2 , with a preform being positioned on its upper surface; and

FIG. 6 is a perspective view of a lower surface of the seal plate ofFIG. 2 , with a preform being positioned on its upper surface.

DETAILED DESCRIPTION

Referring to FIG. 1 , an exemplary fixture 10 in a chemical vaporinfiltration (CVI) vessel is shown for pressure gradient CVI in a stackof porous structures 12, in accordance with various embodiments. Porousstructures 12 may have “OD” (outside diameter) seal plates 14 disposedaround the outside diameter of porous structures 12. Porous structures12 may also have “ID” (inside diameter) seal plates 16 disposed aroundthe inside diameter of porous structures 12. The OD seal plates 14 mayhave an inside diameter 18 slightly less than the porous structureoutside diameter 22, and an outside diameter 20 that may be generallycoterminous with the porous structure outside diameter 44. The ID sealplates 16 may have an outside diameter 24 slightly greater than theporous structure inside diameter 26, and an inside diameter 28 that maybe generally coterminous with the porous structure inside diameter 26.With ID seal plates 16, the porous structure outside diameter 22 may begreater than the outside diameter 24 of the ring like ID seal plate 16.Seal plate 14 and seal plate 16 may be disposed between porousstructures 12 to provide spacing.

In various embodiments, seal plates 14 and seal plates 16 may providesealing between external volume 40 and internal volume 42. A pressuregradient may be maintained between external volume 40 and internalvolume 42 to encourage gas 46 to travel from internal volume 42 throughporous structures 12. Gas 48 moves through porous structures 12 frominternal volume 42 to external volume 40 and exits from vessel 52through a port 50. As gas 48 moves through porous structures 12, gasdeposits may densify porous structures 12.

The porous structure 12 may comprise at least one of carbon, siliconcarbide, silicon nitride, boron carbide, aluminum nitride, titaniumnitride, boron nitride, zirconia, SiCxNy (wherein x is a number in therange from about zero to about 1, and y is a number in the range fromabout zero to about 4/3), silica, alumina, titania (TiO2), and acombination of at least two of the foregoing. Prior to densification,the porous structure may be referred to as a preform. A preform for usein making a carbon/carbon composite, such as a carbon/carbon disk brake,may be referred to as a carbonized preform.

A porous structure may comprise any porous structure derived from afibrous material such as carbon fibers, silicon carbide fibers, and thelike. The carbon fibers may be derived from polyacrylonitrile, rayon(synthetic fiber derived from cellulose), pitch, and the like. Thefibrous material may be in the form of a woven, braided or knittedfabric or a needled felt. The fibrous material may be in the form ofchopped carbon fibers molded to form a preform. Prior to thedensification process, the fibrous material may be formed into a preformhaving any desired shape or form.

The porous structure may be in the form of a disk having any shape suchas, for example, a polygon, a cylinder, a triangle, square, rectangle,pentagon, hexagon, octagon, and the like. In addition, the porousstructure may have an irregular form.

A seal plate in accordance with various embodiments is illustrated inFIG. 2 and is identified by reference numeral 200. Generally, this sealplate 200 may be disposed between an adjacent pair of porous structures12 or preforms within the chemical vapor infiltration and depositionvessel 52 shown in FIG. 1 . The seal plate 200 may be in the form of abody formed from any appropriate material or combination of materials(e.g., Carbon/Carbon Composite). A plurality of fibers of anyappropriate type (e.g., carbon, SiC) may be distributed throughout thebody of the seal plate 200.

The seal plate 200 includes an upper surface 204 and an oppositelydisposed lower surface 206 that are spaced from one another to define athickness for the seal plate 200. An opening 210 extends completelythrough an interior portion of the seal plate 200 to define an innerperimeter 220. Stated another way, the inner perimeter 220 may becharacterized as defining a boundary for the opening 210. This opening210 may define a corresponding portion of the above-noted internalvolume 42 when incorporated by the chemical vapor infiltration anddeposition vessel of FIG. 1 .

An outer perimeter 230 of the seal plate 200 is disposed outwardly ofthe inner perimeter 220. The inner perimeter 220 and outer perimeter 230may be circular, may be concentrically disposed relative to a center 212of the seal plate 200, or both.

A plurality of first channels 240 extend completely through thethickness of the seal plate 200 (e.g., each first channel 240 extendsfrom the upper surface 204 of the seal plate 200 to the lower surface206 of the seal plate 200) and are disposed in spaced relation to oneanother. Each first channel 240 may be characterized as including afirst end 242 and a second end 244. The spacing between the first end242 and the second end 244 of each first channel 240 may becharacterized as coinciding with a length dimension of the correspondingfirst channel 240. In various embodiments, a centerline 260 that extendsbetween the first end 242 and the second end 244 of each first channel240 is disposed along a radius extending from the center 212.

The first end 242 of each first channel 240 is spaced outwardly of theinner perimeter 220, and as such may be characterized as being locatedbetween the inner perimeter 220 and its corresponding second end 244.Each first end 242 may be characterized as being positioned closer tothe inner perimeter 220 that its corresponding second end 244. Thesecond end 244 of each first channel 240 is spaced inwardly of the outerperimeter 230, and as such may be characterized as being located betweenthe outer perimeter 230 and its corresponding first end 242. Each secondend 244 may be characterized as being positioned closer to the outerperimeter 230 that its corresponding first end 242.

In various embodiments, each first channel 240 is wider at itscorresponding second end 244 compared to its corresponding first end 242(e.g., the width dimension being orthogonal to the noted lengthdimension of the first channel 240). In various embodiments, the widthof each first channel 240 progressively increases proceeding from itscorresponding first end 242 to its corresponding second end 244. Thisincrease in width regarding the first channels 240 may be continuous,may be at a constant rate, or both, proceeding along the lengthdimension of the corresponding first channel 240. A minimum width ofeach first channel 240 at its corresponding first end 242 is about 0.25″(6.35 mm) in various embodiments, and is within a range from about 0.5″(12.7 mm) to about 2.0″ (50.8 mm) in various embodiments.

The various first channels 240 may be disposed in equally-spacedrelation to one another (e.g., the first channels 240 may besymmetrically disposed relative to/about the center 212 of the sealplate 200). A common spacing may be used between the inner perimeter 220and the first end 242 of each first channel 240. A common spacing may beused between the outer perimeter 230 and the second end 244 of eachfirst channel 240.

A plurality of second channels 250 extend completely through thethickness of the seal plate 200 (e.g., each second channel 250 extendsfrom the upper surface 204 of the seal plate 200 to the lower surface206 of the seal plate 200) and are disposed in spaced relation to oneanother. The plurality of first channels 240 may be characterized asbeing different in one or more respects than the plurality of secondchannels 250. At least one second channel 250 is disposed between eachadjacent pair of first channels 240 in various embodiments (e.g., asingle second channel 240 in FIG. 2 ).

Each second channel 250 may be characterized as including a first end252 and a second end 254. The spacing between the first end 252 and thesecond end 254 of each second channel 250 may be characterized ascoinciding with a length dimension of the corresponding second channel250. In various embodiments, a centerline 260 that extends between thefirst end 252 and the second end 254 of each second channel 250 isdisposed along a radius emanating from the center 212.

The first end 252 of each second channel 250 is spaced outwardly of theinner perimeter 220, and as such may be characterized as being locatedbetween the inner perimeter 220 and its corresponding second end 254.Each first end 252 may be characterized as being positioned closer tothe inner perimeter 220 that its corresponding second end 254. Thesecond end 254 of each second channel 250 is spaced inwardly of theouter perimeter 230, and as such may be characterized as being locatedbetween the outer perimeter 230 and its corresponding first end 252.Each second end 254 may be characterized as being positioned closer tothe outer perimeter 230 that its corresponding first end 252.

In various embodiments, each second channel 250 is wider at itscorresponding second end 254 compared to its corresponding first end 252(e.g., the width dimension being orthogonal to the noted lengthdimension of the second channel 250). In various embodiments, the widthof each second channel 250 progressively increases proceeding from itscorresponding first end 252 to its corresponding second end 254. Thisincrease in width regarding the second channels 250 may be continuous,may be at a constant rate, or both, proceeding along the lengthdimension of the corresponding second channel 250. A minimum width ofeach second channel 250 at its corresponding first end 252 is about0.25″ (6.35 mm) in various embodiments, and is within a range from about0.5″ (12.7 mm) to about 1″ (25.4 mm) in various embodiments.

The various second channels 250 may be disposed in equally-spacedrelation to one another (e.g., the second channels 250 may besymmetrically disposed relative to/about the center 212 of the sealplate 200). A common spacing may be used between the inner perimeter 220and the first end 252 of each second channel 250. A common spacing maybe used between the outer perimeter 230 and the second end 254 of eachsecond channel 250.

The first end 242 of each first channel 240 may be closer to the innerperimeter 220 than the first end 252 of each second channel 250. Thesecond end 254 of each second channel 250 may be closer to the outerperimeter 230 than the second end 244 of each first channel 240. Thewidth of each first channel 240 at its first end 242 may be greater thanthe width of each second channel 250 at its corresponding first end 252.The width of each first channel 240 at its second end 244 may be greaterthan the width of each second channel 250 at its corresponding secondend 254.

The seal plate 200 includes an inner annulus 270 and an outer annulus280 that are spaced from one another (e.g., in a radial dimension orrelative to the center 212 of the seal plate 200). Each first channel240 and each second channel 250 is disposed entirely between the innerannulus 270 and the outer annulus 280 in various embodiments. Statedanother way none of the first channels 240, nor none of the secondchannels 250, extend into either the inner annulus 270 or the outerannulus 280 in various embodiments. The inner annulus 270 and the outerannulus 280 contribute to/enhance the structural integrity of the sealplate 200.

The inner annulus 270 and the outer annulus 280 may be concentricallydisposed relative to one another. One characterization is that the innerannulus 270 extends from the inner perimeter 220 to the locationcorresponding with first end 242 of each of the plurality of firstchannels 240. Another characterization is that the outer annulus 280extends from the outer perimeter 230 to the location corresponding withthe second end 254 of each of the plurality of second channels 250. Aminimum width of the inner annulus 270 is about 0.25″ (6.35 mm) in onemore embodiments (e.g., measured along a radius emanating from thecenter 212 of the seal plate 200). A minimum width of the outer annulus280 is about 0.25″ (6.35 mm) in one more embodiments (e.g., measuredalong a radius emanating from the center 212 of the seal plate 200). Invarious embodiments, the thickness of the seal plate 200 is no more thanabout 0.5″ (12.7 mm).

A variation of the seal plate 200 of FIG. 2 is presented in FIG. 3 andis identified by reference numeral 200′. Corresponding componentsbetween the seal plate of FIG. 2 and the seal plate 200′ of FIG. 3 areidentified by the same reference numerals, and the discussion presentedabove remains equally applicable unless otherwise noted to the contrary.The seal plate 200′ includes a plurality of inner alignment grooves 272and a plurality of outer alignment grooves 282 that are each formed onthe upper surface 204 of the seal plate 200′ (although such alignmentsgrooves 272, 282 could be formed on both the upper surface 204 and thelower surface 206 of the seal plate 200′). The inner alignment grooves272 may be characterized as being collectively concentrically disposedrelative to the outer alignment grooves 282. Each of the alignmentgrooves 272, 282 may be of any appropriate configuration.

As is shown in FIGS. 3-4 , each inner alignment groove 272 intersects anadjacent pair of first channels 240 at a location that is spacedoutwardly from the first end 242 of each such first channel 240.Although the inner alignment grooves 272 are illustrated as beingcontinuous proceeding between each adjacent pair of first channels 240,such may not be required in each instance (e.g., the inner alignmentgroove 272 could be in the form of one or more segments that are spacedfrom one another proceeding between the corresponding adjacent pair offirst channels 240).

As is further shown in FIGS. 3-4 , each outer alignment groove 282intersects an adjacent pair of second channels 250 at a location that isspaced inwardly from the second end 252 of each such second channel 250.Although the outer alignment grooves 282 are illustrated as beingcontinuous proceeding between each adjacent pair of second channels 250,such may not be required in each instance (e.g., the outer alignmentgroove 282 could be in the form of one or more segments that are spacedfrom one another proceeding between the corresponding adjacent pair ofsecond channels 250).

The inner alignment grooves 272 and the outer alignment grooves 282facilitate the positioning of a preform 310 (e.g., in accordance withthe porous structure 12 discussed above) on the seal plate 200′ and asshown in FIG. 4 . The preform 310 may include an upper preform surface312 and a lower preform surface (that faces the seal plate 200′ in theview shown in FIG. 4 ) that are oppositely disposed and spaced from oneanother (e.g., to define a thickness of the preform 310). This preform310 may further include an inner perimeter 316 and an outer perimeter318 that are spaced from one another (e.g., in a radial dimension). Theinner perimeter 316 and outer perimeter 318 may be concentricallydisposed in various embodiments.

The combination of the preform 310 and the seal plate 200′ may becollectively referred to as a preform stack 300. Another seal plate 200′would typically be positioned on the upper preform surface 312 of thepreform 310 in the FIG. 4 arrangement. The preform stack 300 may includeany appropriate number of preforms 310, with each adjacent pair ofpreforms 310 being disposed between and engaged by a pair of seal plates200′. In any case, the preform stack 300 may be disposed within thechemical vapor infiltration and deposition vessel 52 shown FIG. 1 .

As shown in FIG. 4 , the outer perimeter 318 of the preform 310 is atleast generally aligned with the outer alignment grooves 282 of the sealplate 200′, while the inner perimeter 316 of the preform 310 is at leastgenerally aligned with the inner alignment grooves 272 of the seal plate200′. As such, a portion of each second channel 250 of the seal plate200′ extends beyond the outer perimeter 318 of the preform 310 (in thedirection of the outer perimeter 230 of the seal plate 200′) to define aplurality of outlet ports 256, while a portion of each first channel 240of the seal plate 200′ extends beyond the inner perimeter 316 of thepreform 310 (in the direction of the inner perimeter 220 of the sealplate 200′) to define a plurality of inlet ports 246. FIGS. 5 and 6illustrate the existence of the above-noted inlet ports 246 and outletports 256 for the case where the preform 310 is positioned on the sealplate 200 of FIG. 2 (where the seal plate 200 does not include thealignment features of the seal plate 200′).

A preform stack 300 in accordance with the foregoing may be disposedwithin the chemical vapor infiltration vessel 52 shown FIG. 1 forsimultaneous processing of each preform 310 of the stack 300. As a sealplate 200′ will be disposed between each adjacent pair of preforms 310and engages each of these preforms 310, gas that is within a given firstchannel 240 will simultaneously access a corresponding surface of bothpreforms 310 (e.g., an upper side of a given first channel 240 will beclosed by one preform 310 (except for the ports 246), while a lower sideof the same first channel 240 will be closed by an opposing preform 310(except for the ports 246). The opening 210 of the various seal plates200′ each define a portion of the internal volume 42 of the chemicalvapor infiltration and deposition vessel 52 of FIG. 1 (along with theopen space disposed inwardly of the inner perimeter 316 of each preform310). A pressure gradient may be maintained between the external volume40 and the internal volume 42 of the chemical vapor infiltration anddeposition vessel 52 to encourage gas 46 to travel from internal volume42 through the various preforms 310. Gas 48 moves through the preforms310 from internal volume 42 to external volume 40 and exits from vessel52 through port 50 of the vessel 52. More specifically, gas 48 may entereach of the first channels 240 of the seal plate 200′ through theabove-noted inlet ports 246 (first channels 240), while gas 48 may exiteach of the second channels 250 of the seal plate 200′ through theabove-noted outlet ports 256 (second channels 250). The profile of atleast the plurality of first channels 240 is believed to enhance thedistribution of the gas 48 throughout the preforms 310, namely by theprogressively increasing width of the first channels 240 proceeding inthe direction of their corresponding second ends 244 based upon thehigher pressure existing in the internal volume 42 versus the externalvolume 40. The noted profile of the first channels 240 accounts forthere being more reactive gas toward the inner perimeter 220 of the sealplates 200′ compared to toward the outer perimeter 230 of the seal plate200′ for purposes of enhancing the distribution of gas 48 throughout thevarious preforms 310 (e.g., the width of the first channels 240progressively increases proceeding from the inner perimeter 220 to theouter perimeter 230 of the various seal plates 200′ to account for theconcentration of the gas 48 decreasing proceeding from the innerperimeter 220 to the outer perimeter 230 of the various seal plates200′). The seal plate 200 will function similarly to the seal plate 200′except in relation to the alignment provided by the seal plate 200′.

The seal plates 200, 200′ provide a number of advantages. One isenhanced mechanical strength or a more robust structure, even whenutilizing a thinner profile (e.g., a reduced thickness for the sealplates 200, 200′ in accordance with the foregoing). Another isfacilitating a more uniform densification of preforms 310 duringchemical vapor infiltration and deposition, for instance by providing anincreased gas flow through the first channels 240 (from theircorresponding first ends 242 to their corresponding second ends 252, andthat may correspond with a first direction) based on one or more of theabove-described features/characteristics. Although material may bedeposited on the sidewalls of the first channels 240, the sizing of thefirst channels 240 should increase the amount of time between whichsidewalls of the first channels 240 will need to be cleaned orre-formed—to remove material that has been deposited on the sidewalls ofthe first channels 240 during chemical vapor infiltration anddeposition. The first channels 240 and second channels 250 may alsofacilitate removal of the seal plates 200, 200′ from the preform 310 dueto the reduced contact area between the seal plates 200, 200′ and thepreform 310 (compared to a continuous flat surface or the like).

The foregoing description has been presented for purposes ofillustration and description. Furthermore, the description is notintended to be limited to the form disclosed herein. Consequently,variations and modifications commensurate with the above teachings, andskill and knowledge of the relevant art, are within the scope of thepresent disclosure. Benefits, other advantages, and solutions toproblems have been described herein with regard to specific embodiments.Furthermore, the connecting lines shown in the various figures containedherein are intended to represent exemplary functional relationshipsand/or physical couplings between the various elements. It should benoted that many alternative or additional functional relationships orphysical connections may be present in a practical system. However, thebenefits, advantages, solutions to problems, and any elements that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as critical, required, or essentialfeatures or elements of the disclosure. The scope of the disclosure isaccordingly to be limited by nothing other than the appended claims, inwhich reference to an element in the singular is not intended to mean“one and only one” unless explicitly so stated, but rather “one ormore.” Moreover, where a phrase similar to “at least one of A, B, or C”is used in the claims, it is intended that the phrase be interpreted tomean that A alone may be present in an embodiment, B alone may bepresent in an embodiment, C alone may be present in an embodiment, orthat any combination of the elements A, B and C may be present in asingle embodiment; for example, A and B, A and C, B and C, or A and Band C. Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment,” “an embodiment,”“various embodiments,” etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises,”“comprising,” or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus. Finally, it should beunderstood that any of the above described concepts can be used alone orin combination with any or all of the other above described concepts.Although various embodiments have been disclosed and described, one ofordinary skill in this art would recognize that certain modificationswould come within the scope of this disclosure. Accordingly, thedescription is not intended to be exhaustive or to limit the principlesdescribed or illustrated herein to any precise form. Many modificationsand variations are possible in light of the above teaching.

What is claimed:
 1. A method of processing a preform, comprising thesteps of: disposing a preform in a chamber between a first seal plateand a second seal plate that engage opposing surfaces of the preform,wherein each of the first and second seal plates comprises a pluralityof first channels that each provide an open space that directlyinterfaces with one of the opposing surfaces of the preform; directing agaseous medium into the chamber; introducing the gaseous medium intoeach of the plurality of first channels; increasing a surface area ofthe preform that is exposed to the gaseous medium within each of theplurality of first channels when proceeding in a first direction alongeach of the plurality of first channels; and depositing a materialwithin an interior of the preform using the gaseous medium.
 2. Themethod of any of claim 1, further comprising: disposing a second thepreform in the chamber, wherein the first seal plate is disposed betweenand engages each of the preform and the second the preform; andsimultaneously exposing a portion of each of the preform and the secondthe preform to the gaseous medium within each of the plurality of firstchannels of the first seal plate.
 3. The method of claim 1, furthercomprising: introducing the gaseous medium into the plurality of firstchannels of each of the first and second seal plates through a first endportion of each of the plurality of first channels that extends inwardlybeyond the preform; providing an outlet for the gaseous medium betweeneach adjacent pair of the plurality of channels of the first and secondseal plates, wherein the outlet comprises a plurality of second channelsthat are spaced relative to each of the plurality of first channels; andexiting the gaseous medium from the preform through a second end portionof each of the plurality of second channels that extends outwardlybeyond the preform.
 4. The method of claim 1, wherein the preformcomprises an inner perimeter and an outer perimeter, and wherein thefirst direction is toward the outer perimeter of the preform.
 5. Themethod of claim 4, further comprising: introducing the gaseous mediuminto an inlet zone of the chamber that is located inwardly of the innerperimeter of the preform.
 6. The method of claim 5, wherein the firstdirection is toward an exit zone that is at a lower pressure than theinlet zone and that is located outwardly of the inlet zone.
 7. Themethod of claim 6, wherein each of the first and second seal platescomprise an interior opening, an outer perimeter, and an inner perimeterthat defines a boundary of the interior opening, wherein the inlet zonecomprises the interior opening of each of the first and second sealplates.